Acetylene is a fuel gas largely used in industry and the craft industry for operations of thermal cutting and assembly. It is conditioned in steel cylinders garnished with a porous mass. This latter contains a solvent in which acetylene is dissolved. Recent evolutions appeared in the market and the applications of acetylene (laboratory analyses, precursor in fine chemistry, electronics). Moreover the use of acetylene tends to spread itself for leisure/do-it-yourself applications. These markets require new packagings (reduction in cylinder size), more safety, and the respect of more drastic quality specifications. There is also a need for differentiation compared to traditional and cheaper packagings, often coming from the Central European or Asian countries. These latter however, do not always guarantee the required quality, safety, or environmental features (asbestos-based porous mass). Air Liquide and its partners identified important possibilities for improvements related to: - characteristics and performances of the porous mass - the manufacturing process of this porous mass - the elimination of the harmful effects and the reduction of consumption of energy and water. A series of investigations is necessary to confirm these possibilities and to make them industrial. The main objectives of the OPTIMPAD project are: - lead to an innovative process for porous mass production based on the comprehension/optimization/simplification of the existing process - increase safety performances through a perfectly reproducible quality, conform with new safety requirements imposed by the new markets - increase flow rate performances of the small current acetylene cylinders through an increase of the flow rate/cylinder volume ratio - acquire on the European market a decisive competitive advantage thanks to the development of this new process, to be protected in terms of intellectual property and exploitation. Three R&D sub-projects are thus defined: 1. Understand/control the influence of the raw materials properties (limestone, quicklime, water…) on the manufacturing process. 2. Define and model the physicochemical properties of the porous ceramic material and carry out the correlation with the expected performances of the cylinders in terms of safety, durability and flow rate. 3. Understand/optimize the hydrothermal synthesis parameters of the porous mass. Collaboration between public and private teams will bring the essential academic knowledge to the comprehension of the formation mechanisms of the porous mass during the manufacturing process. This scientific approach associated with the industrial constraints experience (safety, costs, reliability) will lead to a new porous mass manufacturing process for acetylene cylinders, new evaluation criteria, schedules of conditions and working procedures. All innovations and improvements will be tested on an industrial scale on the Air Liquide production site in Villeneuve-sur-Yonne, the last site of this type in France.